[Committed, fortran] PR 60341 invalid union access on string comparison optimization

[Mikael Morin <mikael dot morin at sfr dot fr>]

Hello,

I have just regression tested and committed a patch fixing PR 60341 by
adding two expression type checks before union accesses (it's the same
as the one of the PR).

I plan to backport tomorrow (4.8 and 4.7).

Mikael

Index: gcc/testsuite/gfortran.dg/str_comp_optimize_1.f90
===================================================================
--- gcc/testsuite/gfortran.dg/str_comp_optimize_1.f90	(révision 0)
+++ gcc/testsuite/gfortran.dg/str_comp_optimize_1.f90	(révision 208249)
@@ -0,0 +1,22 @@
+! { dg-do compile }
+! { dg-options "-ffrontend-optimize" }
+!
+! PR fortran/60341
+! An unguarded union access was wrongly enabling a frontend optimization on a
+! string comparison, leading to an ICE.
+!
+! Original testcase from Steve Chapel  <steve.chapel@a2pg.com>.
+! Reduced by Steven G. Kargl  <kargl@gcc.gnu.org>.
+!
+
+      subroutine modelg(ncm)
+      implicit none
+      integer, parameter :: pc = 30, pm = pc - 1
+      integer i
+      character*4 catt(pm,2)
+      integer ncm,iatt(pm,pc)
+      do i=1,ncm
+         if (catt(i,1)//catt(i,2).eq.'central') exit
+      end do
+      iatt(i,4)=1
+      end
Index: gcc/testsuite/ChangeLog
===================================================================
--- gcc/testsuite/ChangeLog	(révision 208248)
+++ gcc/testsuite/ChangeLog	(révision 208249)
@@ -1,3 +1,8 @@
+2014-03-01  Mikael Morin  <mikael@gcc.gnu.org>
+
+	PR fortran/60341
+	* gfortran.dg/str_comp_optimize_1.f90: New test.
+
 2014-03-01  Oleg Endo  <olegendo@gcc.gnu.org>
 
 	PR target/60071
Index: gcc/fortran/ChangeLog
===================================================================
--- gcc/fortran/ChangeLog	(révision 208248)
+++ gcc/fortran/ChangeLog	(révision 208249)
@@ -1,3 +1,9 @@
+2014-03-01  Mikael Morin  <mikael@gcc.gnu.org>
+
+	PR fortran/60341
+	* frontend-passes.c (optimize_comparison): Guard two union accesses
+	with the corresponding tag checks.
+
 2014-02-28  Janus Weil  <janus@gcc.gnu.org>
 
 	PR fortran/60359
Index: gcc/fortran/frontend-passes.c
===================================================================
--- gcc/fortran/frontend-passes.c	(révision 208248)
+++ gcc/fortran/frontend-passes.c	(révision 208249)
@@ -1391,7 +1391,9 @@ optimize_comparison (gfc_expr *e, gfc_intrinsic_op
 	  /* Replace A // B < A // C with B < C, and A // B < C // B
 	     with A < C.  */
 	  if (op1->ts.type == BT_CHARACTER && op2->ts.type == BT_CHARACTER
+	      && op1->expr_type == EXPR_OP
 	      && op1->value.op.op == INTRINSIC_CONCAT
+	      && op2->expr_type == EXPR_OP
 	      && op2->value.op.op == INTRINSIC_CONCAT)
 	    {
 	      gfc_expr *op1_left = op1->value.op.op1;